Discovery and Discipline
by TheMadKatter13
Summary: [TTF 52/SWN 07] Sherlock has been getting off to Mycroft and Greg's coupling all winter break, but it's not enough anymore. His plan to spy on them from the closet is interrupted by them pulling him out into the light... and onto the bed. [Original/actual prompt/summary inside] AU: Adult Mycroft / Shota Sherlock / Adult Mycroft


**SUMMARY: Anonymous said: (1/2)Uni-aged Greg Lestrade and Mycroft Holmes having sex over the Christmas holidays at the Holmes' house and they're trying to be quiet so as not to wake anyone, but Mycroft's room is right next to Sherlock's and he doesn't know that his little brother can hear everything that's being said/happening. Sherlock lays in bed and masturbates while he listens and sometimes he imagines he's Greg and then sometimes Mycroft. One night he hides in Mycroft's closet so he can actually watch while**

 **(2/2) while Greg and Mycroft have sex and sleeping in the closet the whole night will be totally worth it. And Greg and Mycroft put on an effing SHOW for Sherlock because they know he's in the closet and Sherlock watches the entire time, wide eyed, and comes over and over- then Greg and Mycroft "discover" him and decide he needs to be punished. *flies away into the night***

 **AO3 TAGS: Alternate Universe, Adult Mycroft, Adult Greg, Underage Sherlock, Shota Sherlock, Anal, Anal Fingering, Masturbation, Hand Jobs, Voyeurism, Top Greg, Bottom Mycroft, Top Mycroft, Bottom Greg, Incest, Sibling Incest, Virgin Sherlock, First Time, Anal Sex, Bottom Sherlock, Double Penetration, Double Penetration in One Hole, Double Anal Penetration, Plot What Plot/Porn Without Plot, Spitefic**

 **AN: Your prompt is my command. :3**

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They were doing it again. Having sex. Sherlock could hear it through the wall he shared with Mycroft's room. The same wall that their beds were against, mirrored.

 _"Gregory, Gregory, harder."_

 _"You want it harder, Myc? But not deeper? I can do that."_

 _"Deeper! Deeper! Fuck me deeper!"_

Mycroft's boyfriend has been staying with them for Christmas vacation, and every night, he and Mycroft switched who topped and who bottomed. But Sherlock has spent every night, face down ass up in his bed, fingers buried three deep in his hole, his other hand rough around his cock. It's intolerable not being the one who's being touched, and it was almost as intolerable not even being able to see it.

As his brother groaned out his orgasm, and Sherlock bit hard into the pillow as he came into his hand, he resolved that tomorrow night would be different.

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It was lucky that Sherlock had a precedent for disappearing for hours on end, because it meant that no one went looking for him when he disappeared after dinner. When his parents, brother, and his brother's boyfriend retired to the library. They'd been doing it every night, although Sherlock had only joined them once, when he realized they were going to listen to Greg play the piano as the other read. It had been nice to listen to, but Sherlock had only been able to sit still for so long when he'd had experiments to conduct. Tonight, he'd used the opportunity to take his lube and a washcloth and hide in Mycroft's closet.

The wait was long and agonizing, but it was more than worth it when Mycroft and Greg finally tumbled into the room an hour or two later, already kissing and tearing each other's clothes off. They fell onto the bed in a tangle, fabric making way for skin. Mycroft's skin, as covered as it always was, was as pale as Sherlock's, but Greg was a tantalizing tan that Sherlock's mouth ached to touch.

"Fuck, Mycroft, been needing you all night," Greg moaned as Mycroft settled between Greg's open legs.

From inside the closet, looking through the slats, Sherlock could only see that much, so he couldn't see when Mycroft pushed his first finger in, but he could hear it, the slick sound and the groan that Greg let out. Sherlock bit his hand as he pushed his own finger into his arse, his eyes closing for a minute as he imagined it was Mycroft's fingers inside of him.

"Fuck, another one, Myc," Greg groaned, way before Sherlock was ready, but he couldn't object to it without revealing himself, so he dug his teeth even harder into his flesh and forced a second finger in, shivering at the stretch. "Shit, Myc, your fingers-"

Sherlock could only nod in agreement, even though the fingers in him were only his. He knew Mycroft had bigger hands than him, and longer fingers, ones that Sherlock hoped he'd get when he got to be his brother's age. He still had quite a few years to go before then, all of secondary school, really, before he'd be in secondary school too, but Mycroft and Greg would long out of uni by then. Mycroft would always be older, but biology was a roulette and he wouldn't necessarily always be taller.

"You want another one, Gregory?"

"Fuck yeah babe, gimme another one."

He was barely loose enough for the two he had now, but it wouldn't be as real if he didn't follow along with what they were doing, so he hurriedly pulled his fingers out to pour more lube into them and them worked three into his tight sphincter. A whimper worked into his throat and he slapped a hand over his mouth to muffle it. Sherlock scissored his fingers, searching for his prostate, but bent over in the closet with his face pressed to the wall, it was… difficult. But he also wanted to be loose enough in case-

"How about a fourth, my dear?"

Sherlock shuddered and he got caught between agreement and denial, his head making a nod and a shake that turned into a roll.

"Yeah, Myc, give it to me. You know how good to give it to me."

There was a long, low groan, and Sherlock tried not to make the same sound but he wasn't exactly sure how well he managed. And that was just from hearing Greg being fingered. Pushing his own fourth finger in made him want to cry, and he might have actually. His skin felt damp, but nowhere more than his face. Maybe his fingers, soaked in lube and shoved so far up his arse that they were cramping from it.

"You read for my cock, Gregory?" Mycroft muttered, and Sherlock whimpered into his hand. He almost came just from hearing his brother talk so filthy.

"Hurry up and fuck me, Myc. C'mon already," Greg panted, his voice hoarse and desperate, and Sherlock knew it was from the fingering. He wished he could hear himself sound like that after he'd been fingered until he couldn't see straight.

"Like this, Gregory?"

"Aw fuck, Myc, just like that."

The fingering had been almost too quiet to hear, but the fucking… The fucking was _loud_. It was sloppy and wet and Sherlock had to turn his face into his shoulder to muffle the sounds of his pleasure as he moved the hand from his mouth to his cock. He was as careful as he could be to keep himself quiet, to not let his sounds overpower theirs, but his fingers fucking into his ass and the hand around his cock were just as slick and wet as the sounds of Mycroft fucking Greg. He tried to hold out, he tried to make sure that he didn't come before they did, he wanted to come when they did, but the heat in his belly spiraled faster than he could manage and he cried as he wanked off and shot his release all over the inside of Mycroft's closet wall.

In the aftermath, as the tingles faded, he was left panting and collapsed against the wall, his face mashed against the cool surface that was only growing warm and sweaty under his over-heated cheek. The air in the closet was hot and humid and smelled of sex, but it was worth it. Staying in the closet until they fell asleep was still worth it. But he was going to have to come back tomorrow to try again because he'd closed his eyes and he'd forgotten to open them to watch his brother fuck his boyfriend.

There was an ease in the humidity and Sherlock sighed in relief to feel the slight breeze across the back of his neck. And then it clicked that he shouldn't have been able to feel any kind of breeze. Not unless the door was open.

He slowly opened his eyes and horror washed over him at the sight of Mycroft and Greg standing in the closet's doorway, naked and staring with crossed arms and a raised eyebrow each.

"Well well well, what do we have here?" Greg asked in a sardonic drawl.

"Something curious indeed," Mycroft replied, staring down at Sherlock.

"Mycroft-" was all Sherlock managed to get out before his voice shut down in panic.

"You've been naughty, Sherlock," Mycroft said, as if Sherlock hadn't spoken at all. "Sneaking into my room, listening to Gregory and I have sex. Getting lube and semen all over my closet. I believe this calls for punishment."

"Punishment?" Sherlock's brain forced out his voice box in his sudden shock.

"Oh yes, punishment," Greg agreed with a nod. Then they were both reaching for him, hands around his week arms, dragging him into the light of the room.

He stumbled when his trousers, pushed around his knees, hobbled him, but his brother and his brother's boyfriend just lifted him and tossed him on the bed. Sherlock had barely gotten his bearings when Greg climbed in behind him and Mycroft in front of him, bracketing him on both sides.

"You've been listening to us when we've been having private time, haven't you little brother?" Mycroft asked softly, large hands curling around Sherlock's thighs and pulling him up onto Mycroft's kneeling lap. It only served to rub Sherlock's sensitive cock against Mycroft's hard and slick one and he sobbed, wrapping his arms around his brother's neck and burying his face in his shoulder. It was like when they'd been younger, only, they'd never been naked.

"And then you snuck in to spy on us. To watch us fuck, didn't you, Sherly?" Greg whispered in his ear, shuffling in close behind until Sherlock was sandwiched between the two of them. Mycroft's cock pressed against his belly and Greg's against his arse, and for as hard as his heart was pounding, Sherlock couldn't decide whose he wanted in him more.

"Well, the punishment should fit the crime, wouldn't you say, Gregory?" Mycroft mused, sounding far too amused for how panicked Sherlock was.

The hands around his thighs slid up to his arse, pulling him up, and then there was something blunt against his hole. He gasped, but there was no time to say anything before he was being dropped down, and he had a real cock in him for the first time in his life.

A sob tore out his throat and his arms around his brother's neck tightened, the stimulation almost overwhelming. It should have been just like his fingers, but it wasn't. Mycroft was thicker and longer than even four of Sherlock's fingers, and he filled him more than he knew how to process. And he could tell it was Mycroft, because when he came to a rest, it was flat on Mycroft's angled thighs, and there was no longer a cock against his belly, just one against his arse.

"Best be quiet now, little brother," Mycroft whispered in his ear. "Wouldn't want mummy and father to hear you."

Sherlock choked back another sob and nodded against Mycroft's head, and he felt a kiss press to his temple. "Good boy. Now, don't forget that."

Before he could ask why, he felt a finger wriggling into him, tugging at his rim, pulling it away from where it was wrapped around Mycroft's cock. A confused sound worked out his throat, and soft hushes were whispered into the back of his other shoulder.

"This is a punishment, Sherlock," Greg said, finger pushing in fully in aside Mycroft's length. "You may not find this wholly enjoyable."

"I don't understand?" Sherlock croaked, his voice sounding surprisingly wrecked, like how Greg's had sounded. For a split second, he wondered if Greg was still wet and open and why he would give that up.

"I think it'll be clear in a moment, Sherlock," Mycroft said, amusement thick in his voice.

Sherlock frowned, but when a second finger tested the tension of his sphincter, he suddenly understood with terrifying clarity and clenched tight. The fingers gripping his arse cheeks dug in, nails biting into his skin, and then they loosened and pulled away for a confusing moment. Then they came down in a sharp slap and he jerked.

Not even his parents had ever spanked him.

"None of that now, Sherlock," Mycroft reprimanded. "You'll be a good boy and take your punishment or we'll have to punish you again. With something that you won't enjoy at all."

Sherlock gulped and nodded, and then he tried to do as he was asked, tried to loosen up. It took a few tries, and a few false starts, his body immediately tensing when the tips of those two fingers in him started working into him again, but finally he managed.

"Good boy," twin whispers praised him and he shuddered, tensing involuntarily before loosening again.

"Yeah, just like that, Sherlock," Greg whispered behind him, fingers tugging at his rim for a moment before a third finger began to tease at him.

Sherlock felt like crying, completely unsure that he could take it, but he forced his muscles into total relaxation, even when the stretch started to burn, even when the fingers started fucking into him. The hands cupping his arse started to move him, pulling him up and then dropping him back down onto Mycroft's length, and Sherlock found his teeth digging into Mycroft's shoulder to keep himself quiet as he whimpered through the stimulation.

He was already raw from fucking himself in the closet, and this was almost too much too soon. But Mycroft didn't stop. He just kept slowly lifting and dropping Sherlock until Sherlock could catch the rhythm, and he started to help trying to bounce on Mycroft cock.

Unexpectedly, he actually whimpered when the fingers in him left, but then hands on his hips stilled him, keeping him just barely from resting back in Mycroft's lap and on the full length of his cock. Another blunt head pushed against his rim, and he jerked back in a panic.

"I can't!" he whispered, his voice nearly ruined. "It won't fit!" He begged with his eyes for his brother to listen, to understand, but Mycroft's face was terrifyingly blank.

A hand left his arse and rose up to grip his chin in a touch that felt hard enough to bruise. "You can," Mycroft corrected him, voice hard. "And you will."

Sherlock was already shaking his head when Mycroft broke eye contact and looked over Sherlock's shoulder. He nodded once, sharply, and then the hands at Sherlock's waist tightened and forced him _down_.

A hand slapped over his mouth just in time to muffle his yowl as a second cock penetrated him, forcing him so open that he thought he was being torn in half.

"Sh sh sh," was being whispered in both ears by two different voices as tears streamed down his face.

In all his dreams and nightmares, he never knew he could feel so full, that he could be ruined for life in such a way. "Too much," he whimpered, but a hand was still over his mouth.

"Can you be a good, quiet boy for us?" one of them whispered, and Sherlock could no longer tell which one.

He nodded and the hand pulled away, and he whimpered again when a shift of weight brought a shift of the cocks in him. "Too much," he said again, though it came out as more of a mewl than actual words. Still, he must have been understood because hands stroked through his hair in an attempt to calm him, but he couldn't calm down. He was stuffed past the point of breaking with two cocks and his own had apparently grown hard again, for he could feel the rub of it against the softness of Mycroft's stomach.

"Nothing is ever too much, Sherlock."

"You can take it."

Sherlock shook his head but the hands left his hair and returned to his arse and his waist. His mind was too fogged to realize what that meant until they were tightening and lifting him, pulling him off their cocks. He whimpered in relief, but only a moment later, they dropped him down again and his head fell back, mouth open in a silent scream.

"Sh…" someone whispered in his ear. His throat was too tight to respond, his body electric and alive and overwhelmed as the hands pulled him up and dropped him again. "Be a good boy, Sherlock."

The hands at his arse didn't leave, but the ones at his waist moved to his legs, forcing them wider to straddle the knees he was on. Fingers manipulated his feet and toes, bracing him on them, and then the hands were back at his waist, helping the arse-hands with pulling him back up on the two cocks in him. They'd barely gotten any easier to handle, though his hole was more-or-less used to the stretch. It was the rest of him that couldn't handle the stimulation.

"Be a good boy," the voices said again. "Bounce on our cocks for us. This is your punishment. You should be doing most of the work."

Sherlock shook his head, his skull heavy and practically rolling along his shoulders for all his inability to lift it. One hand left him to slide up his rib and over one shoulder to his neck, tipping his head back further until it was resting on a warm, solid surface.

"Yes, Sherlock," the voices repeated, all hands moving, pushing up on him but not pulling him back down, forcing him to awaken the muscles in his jelly-weak legs, forcing him to start bouncing.

It cleared his mind a little, taking back some of his autonomy, but he knew it wasn't being taken back of his own volition. He probably would have just layered there and let them use him until they were done, stripped of the capacity to navigate. There was a solid beat of arousal in his groin, his cock already hard again, already ready to release again, and he tried to drag his arm from the neck it was wrapped around, only for hands to stop him, restrictive bands around his biceps. He whimpered, confused and frustrated, but his thighs were already set into the rhythm and he couldn't help himself from continuing bouncing on the cocks splitting him.

A hand wrapped around his cock and he lost the rhythm for a second, faltering and falling still on his brother and Greg. The hand didn't stop stroking him though, a slow, wet touch that went a long way towards giving him arrhythmia. He half supposed that the glacial movement was to get him to slow down, but he couldn't help chasing a frenzied pace when he started bouncing again. The strange not-heat of orgasm was a slow-build in his groin and every pass of the hand up and down his cock only made it glow brighter.

"Would you like to come, Sherlock?" one of them whispered, and Sherlock nodded frantically, bucking into the hold on his cock and back down onto the cocks in him. "Then what are you waiting for?"

Fingers in his hair pushed his head forward again and his open mouth fitted against a shoulder. He sucked at the salty skin, harder and harder as he bounced as quick as his body was capable, and the hand around his cock slowly started to speed up too. The rise of his orgasm was like a cresting wave, not there until it was, rushing over him like a wave of white noise through his every nerve ending. He bit down hard and moaned as he came, unable to cease his movements as he rode it out.

When it finally ended, he relaxed, letting the bounce of his thighs still, but the hands were back around his waist and under his arse again, keeping him moving. He groaned, confused, and teeth nipped at his neck on one side while lips tickled his earlobe at the other.

"Almost there, Sherlock. We're so close, and we're going to fill you so full."

Sherlock moaned again and clenched down, and the fingers digging into his skin bit in so hard that it felt like nails were going to pierce his skin and bleed him. Twin groans vibrated against his sensitive neck and he shivered when they made his blood flash, the fingers spasming again and holding him still on the thighs holding him up.

Slowly, his breath evened, his heart slow, and his mind turned back on. It helped clear his vision, helped his body process where he was and with who, just around the time the fingers gripping him finally loosened and began to smooth over the sore skin. Mycroft was smiling up at him, expression soft in a way it normally wasn't, and it made Sherlock smile tentatively back.

"Hello, little brother."

A chin hooked onto his shoulder and he turned his head and met Greg's eyes. "Yes, hullo, Sherlock."

"What lesson did you learn from your punishment?" Mycroft asked, pulling Sherlock's eyes back to him with both voice and the tips of fingers on the underside of his chin.

The body behind him shuffled in closer, sandwiching Sherlock between his brother and his brother's boyfriend, making the softening cocks in him shift and making his own sensitive cock brush against Mycroft's stomach, the touch making him sharply inhale.

"Don't spy?" Sherlock ventured, surprised to find his voice hoarse. His brain wasn't fully online, or else he might have been more sure in his answer. Or at least, sure in the correct answer.

"Wrong," Greg breathed against his neck, pressing soft kisses to his sweaty skin, each one making Sherlock shiver and the fingers at his skin twitch.

"Don't get caught spying?" he tried again.

Mycroft's smile became a smirk and he nipped at Sherlock's bottom lip. "Closer."

Sherlock was quiet for a long moment, one in which the two pairs of hands at him began to stroke and knead. Greg was still pressing open-mouth kisses to his skin and Mycroft was watching him with a smile. Sherlock blinked. "Ask permission to spy?"

All hands paused, Greg held away from Sherlock's neck, hot breath wafting over Sherlock's warm skin, and Mycroft's grin grew wide, almost shark-like in victory.

"You were always such a smart boy, Sherlock," Mycroft praised with a soft kiss to Sherlock's lips, and Sherlock beamed. Hands palmed his sternum and belly, nearly spanning his full width.

Greg reached up to turn Sherlock's chin and his kiss was more of a devouring, leaving Sherlock breathless and shaking. A hand moved over and then through his hair, and he leaned forward to rest his forehead against the red mark on Mycroft's shoulders. He shivered harder when fingers passed over his sensitive cock, which nonetheless began to thicken. Just like the cocks still inside him began to thicken again.

"Right genius," Greg agreed from behind him, voice husky as he shuffled forward, squishing Sherlock tighter between his and Mycroft's chests, and feeling like he was trying to work his still half-hard cock further into where Sherlock was stretched wide open and leaking both of their semen. Shuffle. "Right." Thrust. "Fucking." Grunt. "Genius."

FIN

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 **Apparently adding a third character increases the attempted word account. ಠ_ಠ**

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